This invention relates to a fluid flow control device that combines the functions of pressure regulation and selectable flow control. That is, the device regulates the pressure at the outlet to a predetermined value and it responds to a suitable control signal to permit or prevent fluid flow. The device will be referred to herein as a regulator valve. The device is particularly suitable for use in irrigation applications, although it is not limited to this use.
Agricultural irrigation systems typically have a main pipeline and multiple secondary and tertiary distribution lines branching therefrom. Water (with or without added fertilizer, herbicide, insecticide etc.) is supplied to the end of the pipeline. Sprinkler heads, branch laterals, or other distribution means are mounted at intervals along the length of the pipeline for distributing the water. The sprinkler heads or other distribution means can be mounted more or less directly to the main pipeline or at some point along the length of branch distribution laterals that supply the water application devices for growing the crops. In either case the flow rate of water through a sprinkler head or other application device is dependent on the hydraulic pressure at the inlet of the device. That pressure can vary along the length of the pipeline due to friction losses in the pipe and undulations in the local terrain. When it is critical to control the flow rate through an application device a pressure regulator is placed between the pipeline and the device to assure a known hydraulic pressure at the device""s inlet, regardless of its location along the length of the distribution system or undulations in the local terrain. A typical pressure regulator of this type is shown in U.S. Pat. No. 4,543,985.
In some applications it may be also desirable to be able to turn the flow of individual application devices on or off, in addition to controlling the pressure seen by the inlet of the device. Examples where this would be advantageous include a center pivot machine having a swing span pivotably connected to the moving end of the pipeline. The swing span swings into the corners of a field to irrigate portions that would otherwise be missed by the circular pattern covered by the main pipeline. The swing span folds in when the main pipeline is opposite an edge of the field and swings out into a corner. U.S. Pat. Nos. 4,011,990 and 5,695,129 describe such a machine. The main pipeline may stop while the swing span irrigates the corner portion. In that case, it would be desirable to turn off the main pipeline sprinklers. The swing span sprinklers need to be off when the swing span is not irrigating a corner. Another example where on-off control is desirable is where field conditions are known to vary from one location to another and the irrigation machine is programmed to apply water and/or chemicals at differing rates dependent on these known field conditions. A third example of where on-off control is desirable is in an orchard, vineyard, golf course, or other application, where it is desirable to turn on or off only a portion of the distribution devices or branch distribution laterals that supply the water application devices connected to a supply system.
My prior combined pressure regulator and shut-off valve, which is shown and described in U.S. Pat. No. 6,374,853, incorporates a selectable on-off feature. This prior valve of mine utilizes first and second tubular plungers each connected to first and second flexible diaphragms, respectively. This valve is particularly well suited to installation in the tubular drop that connects a sprinkler head to a main or branch pipeline wherein the valve functions as a normally open valve.
The present invention is directed to a combined pressure regulator and shut-off valve that can be installed in a main or a branch pipeline utilizing a disk valve or similar device and an annular seat. The pressure regulating and shut-off mechanisms for the valve are installed in a separate control housing which may be attached to the pipeline shut-off valve housing by a threaded connection, tie bolts or other suitable means of retention. Alternately the control housing could be integrally molded with the valve. A balancing pressure piston located in the control housing is fixedly connected to the disk valve by a rod or a stem. A shut-off piston is movable freely in the control housing relative to the balancing pressure piston attached to the rod. The shut-off piston is equipped with a standoff which engages the balancing pressure piston to maintain a chamber of a minimum length between the two pistons.
In one embodiment of the invention, a compression spring is positioned between the balancing pressure piston and an end wall of the control housing to enable the valve to function as a xe2x80x9cnormally openxe2x80x9d valve. In another embodiment of the invention, a compression spring is installed between the balancing pressure piston and the shut-off piston to enable the valve to function as a xe2x80x9cnormally closedxe2x80x9d valve. The use of a shut-off piston which moves relative to the balancing pressure piston in a chamber of a mini mum length between the pistons allows the placement of ports in the control housing to permit the shut-off pressure and regulating pressure conduits to be connected to the various ports in different arrangements to obtain varying operating functions for the combined pressure regulating and shut-off valve. The shut-off or pilot pressure is usually controlled by a solenoid operated valve or similar device which may be of the self-bleeding type to relieve pressure in the shut-off pressure conduit when the solenoid operated valve is closed while the regulating conduit is usually unobstructed.